The present invention is related to a cooling system for a combustion engine.
In the context of regulations for exhaust gas and consumption, it is necessary to achieve rapid warming up of the combustion engine to its working temperature, in automobiles in particular, because a big part of the relevant emissions and of the consumption is created in the cold operation. The rapid warming is obtained when the amount of cooling fluid circulating through the engine in the cold start is reduced to a minimum degree. However, it has to be taken care with respect to the operational safety that the amount of cooling fluid is sufficient to securely prevent local overheating on critical points of the engine. In addition, legal rules for the defrosting of the glazing at cold outside temperatures must be fulfilled.
In cooling systems for combustion engines, it is distinguished between engine blocks which have only one cycle and such ones which have separate cooling of the head and the block. In the latter case, the water jacket of the engine has two cycles.
Conventionally, one thermostat is provided in single-cycle cooling systems, which is realised as a double valve. Below the working temperature, cooling fluid is conveyed through the cooling passage system of the engine via a heat exchanger for heating (for heating the passenger compartment), the second valve of the thermostat and a bypass. When the working temperature is reached, the thermostat opens and by doing so it throttles the flow across the heat exchanger for heating by the second valve, whereas the main part of the cooling fluid is led through a main cooler.